Patient history also plays an important role in identification and differentiation from other lesions. - A person's dentist will be interested in signs and symptoms that did, and specifically did not, take place. Both immediately preceding, and then throughout the stages of their ulcer's formation and ultimate healing process.

No medical testing (e.g. biopsy, culturing) is typically involved in making a diagnosis. All of the above findings, collectively, can be expected to provide ample evidence for identification on their own. The microscopic characteristics of canker sores are non-specific.

What do canker sores look like? - The stages.

Note: The time frames we've assigned to the different stages outlined below overlap, due to the fact that what is experienced by any one person varies.

Are they contagious?

No, canker sores are neither contagious nor infectious.

Where do canker sores form?

They characteristically only form on the "loose" (movable) tissues of the mouth, meaning those areas where the skin is not tightly bound to the bone underneath. These locations generally involve the "nonkeratinized" (softer, less tough) tissues of the mouth.

Location, location, location.

An important aspect of canker sore identification is based on the fact that they characteristically only form in certain parts of the mouth. These locations are, listed here in order of locations/tissues most affected:

Where canker sores usually form.

The ulcerations form on the "loose" tissues of the mouth.

The inside surface of the lips and cheeks.

The underside (ventral surface) of the tongue.

The mucobuccal fold (the deep trough where the skin of the jawbones and lips/cheeks meet).

The floor of the mouth.

The soft palate.

The tonsillar areas.

(Listed in order of locations/tissues most affected.)

Less common locations.

While rare, it is possible for canker sores to form on keratinized tissues. This includes the top (dorsal) surface of the tongue, the gum tissue that surrounds a person's teeth, hard palate, or even the border of the lips (vermelion border).

When this occurs, the lesion typically involves an extension of a sore already formed on adjacent nonkeratinized tissues.

Healing appearance.

New skin growth (epithelialization) will begin at the edges of the ulceration and then close in from all directions as the healing process progresses.

The original yellow-white coloration of the pseudomembrane that covers the ulceration's surface will transform into a more grey-white appearance as the epithelialization process advances.

Of course, this covering will be gradually replaced at its edges by new pink skin as the size of the lesion shrinks.

The reddened border of the original wound will remain obvious during the early stages of the healing process. Then, as the new skin tissue matures, the border's redness will fade. Complete healing and a normal appearance will return to the affected area within the time frame stated above.

How often do canker sores form?

Another important aspect of canker sore identification involves correlating characteristics associated with their occurrence.

Outbreak frequency.

Once a person has experienced an initial outbreak, the probability of recurrence is high, although the frequency with which this takes place can be quite variable.

A rate of one outbreak every 1 to 3 months might be considered typical (encompassing about 50% of people who get them). 30% of sufferers deal with their presence on a monthly basis.

That means many people will only be plagued by a few episodes a year, while others will experience nearly continuous outbreaks and therefore will never be completely free of ulcers for any extended period of time.

Incidence rates / Prevalence.

Most sources tend to suggest that around 20% of the general population experiences canker sores, although actual reports from studies have ranged from 5% to 66%.

A person's first outbreak will typically take place between the ages of 10 and 20 years, and then decrease in frequency and severity with age.

Lesions are most prevalent in people ages 10 to 40. 80% of those affected will experience their first lesion prior to the age of 30.

It's been suggested that women are more likely to experience sores than men but not all studies confirm this fact.

A family (genetic) predisposition seems to exist. Children with parents who get canker sores have a 90% chance of getting them too, as compared to a 20% chance for those whose parents don't.

A person's risk seems to be unrelated to race. But people who live in North America are more likely to suffer with them, as opposed to people who live in other world-wide geographic areas.

Non-smokers and people in upper socioeconomic groups are more likely to experience outbreaks.

What are "major aphthous ulcers"?

Canker sores like we have described above are formally termed "recurrent minor aphthous ulcers." They are the type of canker lesion experienced by 80% of sufferers.

Beyond these "minor" lesions, there's another type of aphthous ulcer referred to as "major aphthae" or Sutton's ulcers. And in comparison to the minor variety they are a large deep ulceration whose healing is characteristically slower and more painful.

Characteristics.

Unlike minor aphthae, the major kind forms on all types of oral tissues (both keratinized and nonkeratinized tissues). They frequently form on the lips, soft palate or fauces of the throat.

They can approach 1/2 inch (or more) in diameter and may cause regional or even facial swelling.

Their healing usually takes between 10 and 40 days. However it may take some months (even as new ulcers are forming).